Two- and Three-Dimensional Smectic Ordering of Single-Handed Helical Polymers(13)

Spectroscopicdataofpoly-L-1200:IR(KBr,cm-1):3276(νN-H),1751(νCdOester),1635(amideI),1535(amideII);1HNMR(CDCl3,55°C):δ0.86(broad,CH3,3H),1.24(broad,CH2,14H),1.53(broad,CH3andCH2,5H),4.07(broad,CH2,2H),4.47(broad,CH,1H),4.8-7.7(broad,aromatic,4H),7.9-9.0(broad,NH,1H);[R]25D-1083°(c0.1,chloroform).Anal.Calcd(%)for(C21H30N2O3)n:C,70.36;H,8.44;N,7.81.Found:C,70.09;H,8.32;N,7.63.

Spectroscopicdataofpoly-L-1200(-):IR(KBr,cm-1):3277(νN-H),1740(νCdOester),1635(amideI),1533(amideII);1HNMR(CDCl3,55°C):δ0.87(broad,CH3,3H),1.24(broad,CH2,14H),1.53(broad,CH3andCH2,5H),4.08(broad,CH2,2H),4.51(broad,CH,1H),4.8-7.7(broad,aromatic,4H),7.9-9.0(broad,NH,1H);[R]25D-1714°(c0.1,chloroform).Anal.Calcd(%)for(C21H30N2O3)n:C,70.36;H,8.44;N,7.81.Found:C,70.34;H,8.36;N,7.70.

WAXDMeasurements.Theorientedhelicalpoly-L-1(-)andpoly-L-1(+)films(ca.20µmthickness)fortheX-rayanalyseswerepreparedfromconcentratedLCbenzenesolutionsinanelectricfieldof6000V/cm.TheWAXDpatternsoftheorientedpoly-L-1(-)andpoly-L-1(+)filmswithdifferentrangesofsensitivitiestoshowboththestrongandweakreflections(FigureS2),wherethemainlayerlineshavebeenindicatedandtheindicesofthereflectionsarelabeled,exhibitdiffuseequatorialreflections,andseveralmeridionalandoff-meridionalreflectionsonthelayerlines,althoughtheonlybroadreflectionswereobservedinthediffractionpatternofpoly-L-1(+)probablyduetoitsrelativelylowmolecularweight.Thereflectionsinthediffractionpatternsofpoly-L-1(-)andpoly-L-1(+)canbeproperlyindexedwithhexagonallattices;a)26.78Å,c)13.05Å,anda)26.45Å,c)13.20Å,respectively.ThespacingsandmirrorindicesofthereflectionsarelistedinTableS1.Althoughwecouldnotobserveameridionalreflectiononthe15thlayerline(0.87Å)evenwhentheX-raymeasurementswereperformedusingacylindricalcamerawiththesamplestiltedca.62°normaltothebeam,themostprobablestructureofthehelicalpoly-L-1(-)andpoly-L-1(+)canbeproposedtobea15/4helixbyconsideringthelayerlineintensitiesobservedinthediffractionpatternsandthedensitymeasurement14andcalculationresults.

SAXSMeasurements.Theorientedhelicalpoly-L-1(-),poly-D-1(+),andpoly-L-150(-)filmsfortheSAXSmeasurementswerepreparedbygradualsolventevaporationofaconcentratedLCchloroformsolutionofeachpolymer(initialconcentration:ca.20wt

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%)inaborosilicateglasscapillarytubeinahighmagneticfield(11.75T)usingaVarianAS500NMRinstrument,afterthepolymershadbeentreatedwithCuClinpiperidinetoeliminatethePdresiduesatthepolymerends,followedbySECfractionation.Wenotedthatthesmecticlayerreflectionscouldnotbeobservedforthemagnetic-orientedpolymersbearingtheterminalPdresiduespreparedundertheidenticalconditions;thereasonisnotclear,butprobablyduetothehighatomicscatteringfactorofthePdmetalsatthepolymerends.

Atypicalprocedurefortheeliminationreactionisdescribedbelow(seeScheme1).Toasolutionofpoly-L-1(-)(41mg)inpiperidine(4mL)wasaddedasolutionofCuClinpiperidine(28.8mM,50µL;2equivtothepolymer)atambienttemperature.Themixturewasthenstirredat120°Cunderadryargonatmosphere.After9h,theresultingpolymerwasprecipitatedinalargeamountofacetonitrile,collectedbyfiltration,andwashedwithacetonitrile.Thepolymerwasthendissolvedinasmallamountofchloroformandprecipitatedinacetonitrilewhichwasrepeatedasecondtime.Theobtainedpolymerhadabroadpolydispersity(Mw/Mn)1.20),andthepolymerwasfractionatedbySECusingTHFcontaining0.1wt%tetra-n-butylam-moniumbromideastheeluent,yieldingpoly-L-1(-)withanarrowpolydispersity(25mg,61%yield,Mn)6.75×104,Mw/Mn)1.04, 364)-21.8)afterbeingpurifiedbyreprecipitationanddriedinvacuoatambienttemperaturefor10h.Inthesameway,thePd-eliminatedpoly-L-150(-)(Mn)2.83×104,Mw/Mn)1.03, 364)-19.9)andpoly-D-1(+)(Mn)5.13×104,Mw/Mn)1.03, 364)+21.6)wereprepared,andthesesampleswereusedfortheSR-SAXSmeasurements.TheresultingPd-eliminatedpolymersgavealmostidenticalCD,absorption,andNMRspectratothoseoftheoriginalpolymers,althoughtheirmolecularweightsandMWDswereslightlychanged.TheseresultssuggestthatthePdeliminationproceduredidnotcauseasubstantialchangeofthehelicalstructuresoftheoriginalpolymers.

SEC-MALSMeasurements.TheSEC-MALSmeasurementswerecarriedoutwithTHFcontaining0.1wt%tetra-n-butylammoniumbromideusedastheeluentattheflowrateof0.5mL/min.Astandardpolystyrene(Mw)30500(PolymerLaboratories,Shropshire,U.K.))wasusedtocalculatethedeviceconstants,suchastheinterdetectordelay,interdetectorbandbroadening,andlight-scatteringdetectornormalization.Poly-L-1(-)andpoly-L-1(+)werecompletelydissolvedintheeluentattheconcentrationof0.1-0.2%(wt/vol)undergentlestirringfor1-2hbeforeinjection.TheevaluationsofthemolecularweightswereaccomplishedusingASTRAVsoftware(version5.1.3.0).Thedn/dcvaluesofpoly-L-1(-)andpoly-L-1(+)intheeluentusedfortheevaluationswere0.1369and0.1367mL/g,respectively.

AFMMeasurements.Stocksolutionsofpoly-L-1,poly-L-1(+),poly-L-1(-),poly-D-1(+),andpoly-L-1200(-)indrybenzeneorTHF(0.015or0.02mg/mL)wereprepared.SamplesfortheAFMmeasure-mentswerepreparedbycasting20µLaliquotsofthestocksolutionsofthepolymers.ThecastingwasdoneatroomtemperatureonfreshlycleavedHOPGunderbenzeneorTHFvaporatmospheres.AfterthepolymershadbeendepositedontheHOPG,theHOPGsubstrateswerefurtherexposedtobenzeneorTHFvaporsfor12or2h,respectively,andthenthesubstratesweredriedundervacuumfor2haccordingtothereportedprocedure.8,16Theorganicsolventvaporswerepreparedbyputting1mLofbenzeneorTHFintoa2-mLflaskthatwasinsidea50-mLflask,andtheHOPGsubstrateswerethenplacedinthe50-mLflask.ThetypicalsettingsoftheAFMforthehigh-magnificationobservationswereasfollows:amplitude1.0-1.5V,setpoint0.9-1.4V,scanrate2.5Hz.TheNanoscopeimageprocessingsoftwarewasusedfortheimageanalysis.

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